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Diagnostic Item 21: Communication with no ECUs is possible (CAN-C-Mid).
 
 
cautionWhen servicing a CAN bus line, ground yourself by touching a metal object such as an unpainted water pipe. If you fail to do, a component connected to the CAN bus line may be broken.
 
 
TROUBLESHOOTING HINTS
  • Malfunction in CAN-C-Mid (short to ground or power supply, wire short to one another)
  • Malfunction in the ECUs which are interconnected via CAN-C-Mid (internal error)
  • Malfunction (open circuit) of wiring harness, connector (s) between the ETACS-ECU and joint connector(s)
 
 
DIAGNOSIS
Required Special Tools:
  • MB991223: Harness Set
  • MB992006: Extra Fine Probe
STEP 1. Check the CAN-C-Mid for short to power supply. Voltage measurement at ETACS-ECU connector by backprobing.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Connect the negative battery terminal, and turn the ignition switch to the "ON" position.
(2) Voltage between ETACS-ECU connector terminal No.17 (CAN_H) and body ground by backprobing
OK: Less than 4.0 volts
(3) Voltage between ETACS-ECU connector terminal No.16 (CAN_L) and body ground by backprobing
OK: Less than 4.0 volts
Is the check result normal?
: Go to Step 2.
: Perform diagnostic item 22 "Diagnose shorts in the power supply to CAN-C-Mid". Refer to .
 
STEP 2. Check the CAN-C-Mid for short to ground. Resistance measurement at ETACS-ECU connector by backprobing.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Turn the ignition switch to the "LOCK" (OFF) position.
(2)
cautionWhen measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.
(3) Resistance between ETACS-ECU connector terminal No.17 (CAN_H) and body ground by backprobing
OK: 1 kΩ or more
(4) Resistance between ETACS-ECU connector terminal No.16 (CAN_L) and body ground by backprobing
OK: 1 kΩ or more
Is the check result normal?
: Go to Step 3.
: Perform diagnostic item 23 "Diagnose shorts in the ground to CAN-C-Mid". Refer to .
 
STEP 3. Check the CAN-C-Mid for short to each other. Resistance measurement at ETACS-ECU connector by backprobing.
cautionA digital multimeter should be used. For details refer to .
cautionThe test wiring harness should be used. For details refer to .
(1) Turn the ignition switch to the "LOCK" (OFF) position.
(2)
cautionWhen measuring the resistance, disconnect the negative battery terminal. For details refer to .
Ensure that the negative battery terminal is disconnected.
(3) Resistance between ETACS-ECU connector terminal Nos.17 and 16 by backprobing
OK: 60 ± 10 ohms
Is the check result normal?
: The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).
: Perform diagnostic Item 24 "Diagnose shorts between CAN_H and L lines (CAN-C-Mid)". Refer to .
: Check the wires between ETACS-ECU connector and joint connector (CAN5) for open circuit, and check the terminal resistors in the combination meter and the ETACS-ECU for open circuit. Then repair or replace if necessary.